There are two basic families of cabinet drawer and door locks: deadlocking and latch locking types of locks, and cam-type locks. Both families of locks are used on cabinet drawers and doors such as those found on office desks, credenzas, and interior cabinetry. In the former family, an elongated bolt moves in a reciprocating manner into and out of a bolt housing between locked and unlocked positions, respectively, upon actuation of a key. In the latter family, an elongated bolt moves along an arcuate path, between locked and unlocked positions. In the cam family of locks, an angular rotation of 90 degrees is typically sufficient to determine the locked and unlocked positions.
Both families of locks may have their bolts actuated by either pin tumbler cylinder and plug assemblies, or disk tumbler-type assemblies. The disk tumbler-type assemblies are the least expensive and historically have been used in the cam type of lock. A lock of this type is shown in U.S. Pat. No. 3,863,476 to Patriquin, in which a plurality of spring-loaded plates in a plug are biased to position a protrusion from the plates into an elongated trough or cavity in an externally threaded lock body. Interference between the protrusions and sidewalls of the lock body trough prevent rotation of the plug. Upon insertion of a key into a keyway of the plug, the plates retract and the protrusions are withdrawn from the trough. Thereupon, the plug can rotate within the threaded lock body. The plug is longitudinally restrained within the lock body by a spring-loaded clip. The bolt is typically journaled for rotation with and screwed onto a longitudinal extension at the rear of the plug.
Over the years, it has become desirable to provide cam locks with a pin tumbler rather than a disk tumbler system. In the pin tumbler system, the disk plates are replaced with a series of cylindrical pins, which reside in bores in the plug. These “bottom pins” have differing lengths corresponding to protrusions and valleys in a mating key. The lock body or cylinder is provided with a corresponding series of spring-loaded top pins that can drop down into the bores in the plug into which the lower pins reside. When a key is inserted into the plug keyway, the top pins and bottom pins form a shear line at the interface of the plug and cylinder, allowing the plug to rotate freely. A particular problem with this type of lock is that the key can be inserted or removed only when the top and bottom pins are in alignment (typically the 12 o'clock position).
In contrast to cam type locks, deadlocking and latch locking types of locks have a bolt that reciprocates transversely with respect to a keyway of the lock. In the deadlocking type of lock, the bolt remains in an extended or retracted position and is not translatable therefrom without operation of the key. In a latch locking type of lock, the bolt has a curvature on the end thereof and is spring-biased to the extended position. Transverse pressure on the curved portion of the bolt urges the bolt against the spring bias to a retracted position so that a cabinet door or drawer can be closed without the use of a key. The latch locking type of cabinet lock can also be provided with a separate deadlocking bolt that prevents “jimmying” of the spring-biased latch bolt when the deadlocking portion of the latch bolt is depressed, such as by a strike plate. An example of a rekeyable pin tumbler type of deadlocking cabinet lock is shown in U.S. Pat. No. 4,899,563, assigned to the Frank J. Martin Company, Seattle, Wash.; an example of a deadlocking, self-latching cabinet door and drawer deadlocking latch lock is shown in U.S. Pat. No. 5,657,652, assigned to the same assignee.
In all of the above types of locks, either a disk tumbler type of assembly or a pin tumbler type of assembly may be used. It is known to those of ordinary skill in this art, particularly with respect to the pin tumbler type of locks, that it is desirable to maintain the orientation of the bottom pins, top pins, and springs in a vertical orientation to prevent the lock from jamming, which may occur if the pins are not maintained in a vertical position (e.g., the pins are lying on their side in a horizontal plane). For this reason, cabinet door and drawer locks are typically sold in left-hand, right-hand, vertical-hand, and inverted-hand versions in which the bolt is presented in four orthogonal directions while the keyway is always maintained in the vertical position. The assignee of the present invention and/or its predecessors in interest have sold a variety of locks in these configurations, such as the Olympus Lock Company's Models 997 and 996 door and drawer latch locks. Clearly, the maintenance of stock on hand of four different varieties of every type of lock is costly, and a clear need exists for a single type of latch lock that is field configurable to any one of the above four orthogonal positions. However, complex assemblies and parts that are difficult or expensive to manufacture are generally undesirable in the lock art. Simple assemblies generally permit reduced manufacturing costs, improved reliability, and serviceability in the field. In addition, locks that require special tools to facilitate disassembly for rekeying purposes or the like have been historically disfavored by locksmiths. As a result, the development of a commercially viable, field-reversible four-way latch lock has eluded the industry. Thus, a need exists for a low-cost, pin tumbler self-latching cabinet door and drawer lock that is field reversible by locksmiths to any one of four orthogonal positions.